Weak lensing is proving to be a powerful probe of large-scale matter distribution and will allow for high-precision tests of cosmology in the coming decade. I will start the talk with weak lensing modelling and likelihood analysis challenges and how we address them in the Dark Energy Survey (DES), a precursor of Stage-IV weak lensing surveys such as Euclid and LSST. I will then give an overview of the status of tests of gravity on cosmic scales, with weak lensing, as well as CMB lensing, showing results from DES Y3 and preliminary results using ACT lensing data. Our analyses are setting the scene for future tests of cosmology: I will end with prospects for stage-IV surveys.